1. Field of the Invention
The invention relates to the field of vibratory z-axis gyroscopes with at least two coupled masses operating in anti-phase motion.
2. Description of the Prior Art
Conventional tuning fork designs with linear anti-phase drive-modes present several major drawbacks: presence of the parasitic low-frequency structural mode of in-phase vibration, limitation of the maximal achievable sense-mode quality factor by approximately half of the drive-mode quality factor due to substrate energy dissipation caused by the torque imbalance, and difficulty of maintaining mode matched condition over the practical temperature ranges.
The operation of micromachined vibratory gyroscopes is based on a transfer of energy between two modes of vibration caused by the Coriolis effect. When the drive- and sense-mode resonant frequencies are equal, or mode-matched, the sensor output is increased proportionally to the sense-mode quality factor. Anti-phase driven tuning fork architectures are often used due to their ability to reject common mode acceleration inputs.
Conventional tuning fork designs with linear anti-phase drive-modes present several major drawbacks: presence of the parasitic low-frequency structural mode of in-phase vibrations, limitation of the maximal achievable sense-mode quality factor by approximately half of the drive-mode quality factor due to substrate energy dissipation caused by the torque imbalance, and difficulty of maintaining mode-matched condition over the practical temperature ranges.